1. Field of the Invention
The present invention relates to a post structure, a semiconductor device and a light emitting device using the structure, and a method for forming the same. More particularly, the present invention relates to a post structure, a semiconductor device and a light emitting device using the structure, and a method for forming the same, which is capable of forming the nanometer-scale post structure having a repetitive pattern by using an etching process.
2. Discussion of the Related Art
Recently, a semiconductor fabrication technology has been developed up to a newel level while overcoming several physical limits. It can be said that overcoming a spatial limit via a three-dimensional design is one of factors making such a development possible.
In the recent three-dimensional design for a semiconductor device, it has attempted to expand a unit structure to a three-dimensional structure, beyond the level of simply laminating identical repetitive two-dimensional structures one above another. This is a success in view of a greater capacity and surface area.
However, the three-dimensional design has a need for a very sophisticated photo-lithography method, and thus, suffers from excessive design costs and high process precision.
Moreover, a higher process precision is required to endow each unit pattern with a polygonal shape. Therefore, although such a newel technology can be realized, a degradation in productivity is inevitable. In conclusion, the newel three-dimensional design technology cannot be utilized in mass production.
Meanwhile, in the case of a light emitting device and a display device using the same, a technology for providing the light emitting device with a rough surface for the purpose of increasing light extraction efficiency of the device, or a technology for forming a nanometer-scale surface structure such as photonic crystal has been used.
To achieve the nanometer-scale surface structure, conventionally, a dry etching method has been mainly used. In particular, a GaN-based semiconductor diode device has a great difficulty in the implementation of a wet etching method because of an excessively high hardness of GaN.
However, the dry etching method has a problem in that a mask for covering a part of the structure to be etched is disappeared in the course of etching and thus, an etching height is inevitably limited according to the thickness of the mask. Moreover, due to the disappearance of the mask, there is a drawback in that the structure may have an inclined plane rather than being etched orthogonally.
For these reasons, there is the rise of a need for a method of forming a post structure suitable for mass production via a wet etching process because the wet etching process has no limit in etching height and etching time.